Otherwise I have no complain.

Surprisingly accurate. When I go smoothly CW, measuring out 180 degrees in about 4 seconds, I often get within 1 degree. When I go CCW, however, it seems to be no better than 2 degrees, and often 3 or 4 degrees off. This is still around 2% accuracy, which is very good. I get this kind of error routinely, even if I let the gyro stabilize to minimize drift. It thus might be necessary to have two calibration values: one for CW and one for CCW turns.I am also having troubles seeing that the calibration I'm setting is doing anything. While I really like the concept of how you calibrate it, it is a unclear when exactly it is using the calibration for its output. Since calibrating depends on measuring the angle with calibration off, it should be very straight-foward to have calibration on or off in the settings, and even to have a color indication in the goniometer view itself so that we know calibration is or isn't taken into account.Other than that, I only have one small feature request: present a drop-down menu of angle formatting choices, since there are so many to toggle through.

I must say the accuracy is excellent. I used it to get an angle for my compound mitter saw. I drew the line on the board at the angle I needed and use this app as a protractor. Then set up my saw and put the board on it. The line and the saw where exactly the same.I haven't used it in to many situations yet but if ever lets me down I will change my review. But I thinks it's worth money.I even tried it where I new it wasn't going to work like a compass just to see if you needed any special external signal and it still worked .This is important to me cause I work in a Steel Mill in basements and places with no reception at all.

Very good use of the gyroscope as a level. Looks great and responds well. Unfortunately it has to be calibrated after every use, as it seems the gyroscope has a tendency to lose track after moving it around. I think it might be an issue with the hardware itself since I see it in other gyro apps, such as gun range. Does anyone else have this problem? (calibrate to a surface, then tilt it left and right a few times and put it back)